Simulation of Nile tilapia (Oreochromis niloticus niloticus L.) culture in ponds, through individual-based modelling, using a population dynamic approach

A simulation model for the production of the Nile tilapia (Oreochromis niloticus niloticus L.) for mixed- or mono-sex culture and for poly-culture with the African catfish (Clarias gariepinus Burchell 1822) or African snakehead (Parachanna obscura Gunther 1861) is presented. The model is based on an exponential decay model used in population dynamics and follows an individual-based approach. The model consists of a tilapia sub-model representing population dynamics, growth and recruitment and a predator sub-model representing the predation process and population dynamics and growth of the used predator. The model was calibrated with data on mixed- or mono-sex culture of Nile tilapia and for poly-culture with the African catfish or African snakehead obtained in Congo Brazzaville and validated with similar data from the Philippines, Thailand and the Ivory Coast. The model visualized major underlying processes in tilapia farming and aspects for further improvement of the model; growth is one of the most sensitive input parameters and should be quantitatively related to feeding level and feed quality; length at first maturity and quantification of the recruitment of Nile tilapia has a relatively large influence and recruitment should be related to the length of the females; prey-predator relations are too coarse and should be more fine-tuned with the relation between prey size and predator size. Incorporation of these features would provide the basis of a model that can serve as a predictive and decision-making support tool.